Aquarium



FIG. 1 is a front elevational view of an aquarium showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a rear elevational view thereof; and

FIG. 5 is a right side elevational view thereof.

The broken line representation of fish and plants in FIGS. 1 and 4 is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for an aquarium, as shown and described. 